Amyl esters of 3-methyl-delta4-tetrahydrophthalic acid



Patented Mar. 3, 1942 v UNITED: ,STATES P 'reNr oFr 2,275,386 ICE AMYL ESTERS OF 3-METHYL-Ad- TETRAHYDROPHTHALIC ACID Frank J. Soday, Upper Darby, Pa, assignor to The United Gas Improvement Company, a, cor.- poration of Pennsylvania No Drawing. Application June it, 31939, i

- Serial No. 278,481

9 Claims. (circa-41cc) The present inventionrelates to new compositions of matter and to methodsfor their preparation.

More particularly, this'invention pertains to amyl esters of .3-methyl-A4-tetrahydrophthalic acid'and its anhydride, and processes for the preparation of these new esters.

This invention is based upon the discovery that esters possessing very valuable properties can be obtained by the reaction of amyl alcohols, or mixtures thereof with 3-methyl-A4-tetrahydrophthalic acid,lits anhydride, or other derivative, or with mixtures containing the acid, the anhydride, and/or other derivative.

' 3-methyl-A4-tetrahydrophthalic acid is a pipis the equivalent of the acid in the preparation of the esters disclosed herein.

It is an object of the present invention to provide as new compositions of matter, amyl esters tives with primary, secondary and tertiary amyl alcohols, and mixtures and derivatives of these alcohols. invention will be apparent to those skilled in the art from the following description.

B-m'ethyl-Ad-tetrahydrophthalic acid or its anhydride maybe obtained in a number of ways. For example, the anhydride may be prepared through the reaction of piperylene with maleic anhydride. This reaction may be illustrated structurally as follows: a

.mog /H E 0 H\ /C\H o c-o .o' c-o I CHFCH-CH=QHOH3 o o s H o H 0 tr 0 Piperylene maleic 3-methyl-A4- anhydride 'tetrahydrophthalic anhydride form the corresponding acid, 3-methyl-A4-tetrahydrophthalic acid, for instance, by mixture with water.

Illustrative of the reaction by which 3-methyl- Ad-tetrahydrophthalic anhydride may be prepared is the example given below as Example 1.

Piperylene, or hydrocarbon fractions containing any portion of piperylene may be used to react with malelc anhydride. The piperylene may be obtained synthetically, or from fractions obtained by condensation in the manufacture of carburetted water gas, oil gas, refinery gas, or coke oven gas,or from similar sources.

' of 3-methyl-A4-tetrahydrophthalic acid and processes for theirpreparation and purification, More specifically, it is an object of the invention to provide new organic compounds comprising fluids which are essentially colorless and odorless and which are suitable for use alone or in combination with-other substances as plasticizers in the formulation of lacquers, particularly those lacquers containing cellulose esters. Still another object is the provislon'of new compounds particularly valuable as'plasticizers for synthetic and natural resins and plastics in general. A still further object of the invention is to provide new compounds which maybe used as chemical, intermediates in chemical synthesis. Another object is the provision of a process for effecting reactions between 3-methylA4-tetrahydrophthalic acid, its anhydride and/or its deriva- For example,-a sample of light oil, obtained in the manufacture of oil gas, under certain conditions, may be fractionated to obtain a cut containing, say from 30 to piperylene, in addition to various other quantities of other unsaturated hydrocarbons. Cyclopentadiene and perhaps similar unsaturated hydrocarbons which may be present in a piperylene fraction may, if

desired, be removed among other-ways by heating.

thematerial, say at C., in a closed vessel for several hours, followed by the distillation of the unchanged piperylene from the polymers thus formed. Isoprene may :also be present. While a concentration of piperyleneof at least 30% is preferred, lower concentrations may be employed.

The piperylene or piperylene fraction may be reacted with maleic anhydride or maleic acid or mixtures of these to produce '3-methyl-A4-tetravhydrophthalic anhydride by warming a mixture.

of the reagents. The reactants may be mixed, say in substantially molar quantities, and allowed to react at room temperatures or at elevated tem- Other objects and advantages of the The anhydride may be readily hydrolyzed to binol CH3CH2(CH3) CHCHzOH,

peratures until substantially complete conversion has been obtained.

A preferred embodiment of effecting the reaction is to mix the reactants andallow the mixture to stand at room a period of time.

However, the process is use of any definite heating time or temperature. The reactants may be combined as such, or in solution form in a suitable solvent or solvents. Suitable solvents for this purpose include aromatic hydrocarbons, chlorinated solvents, esters, ethers, and the like. 3-methyl-A4-tetrahydrotemperature, or lower, for

phthalic anhydride is obtained in good yield as a result of this reaction. readily hydrolyzed to 3-methyl-A4-tetrahydrophthalic acid if desired as above pointed out.

Illustrative of one of the methods for preparing 3-methyl-A4-tetrahydrophthalic anhydride is the following example:

, Example 1 An enameled vessel of about five gallons capacity was equipped with a stirrer, safety valve and manometer. A mixture of 1475 grams (15.06 mols) of maleicanhydride and 1589 grams (2270 cc.) of a piperylene cut containing 83.7% piperylene by weight (19.6 mols of piperylene) was placed in the vessel together with one liter of acetone. The temperature was reduced to C. and the mixture'stirred for a period of one The anhydride may be hour, whereupon an exothermic reaction occurred.

The mixture was maintained at a temperature of 0 C. for an additional period of 48 hours.

after which the solution was decanted from the piperylene which did not enter into the reaction was recovered.

Ester formation Through the reaction of 3-methyl-A4-tetrahy-. drophthalic acid or its anhydride with amyl alcohols, there may be produced amyl esters of the acid having properties which make such esters valuable in a number of industrial fields.

Among the amyl alcohols which may be reacted with 3 -methyl-A4-tetrahydrophthalic acid or its anhydride are the following: normal amyl alcohol CH3(CH2)3CH2OH, secondary butyl carisoamyl alcohol (CH3) 2CHCH2CH2OH, neopentyl alcohol (CH3) 3CCH2OH pentanol-2 (CH3CH2CH2) (CH3) CI-IOH, pentanol- 3 (C2H5)2CHOH, methylisopropyl carbinol (CH3)2CHCHOHCH3, and tertiary amyl alcohol (CI-IsCHz) (CH3)2COH. In addition, any desired mixture of the foregoing alcohols, or any mixture of alcohols containing one or more of the foregoing alcohols, may be used in the preparation of esters of 3-methyl-A4-tetrahydrophthalic acid. For example, a commercial mixture of not restricted to the amyl alcohols (Pentasol) having the following approximate composition, sec. butyl carbinol- 32%,. n-amyl alcohol-26%, pentanol-318%, isoamyl alcohol--l6%, and pentanol-2-8%, has been found to be especially desirable for the production of these derivatives.

The esters obtained through such reactions theoretically have the following general structural formula.

CH: H

(I CII-COOC5Hi1 o-ooocmn ,H o H H H: Amyl ester of 3-methyl-ni-tetrahydrophthalic acid.

The amyl esters of 3-methyl-A4-tetrahydrophthalic acid may be made in different ways.

One convenient way for the preparation of such esters is to react 3-methyl-A4-tetrahydrophthalic acid or its anhydride with the desired amyl alcohol by heating the reacting constituents to the boiling point of the alcohol while employing a reflux condenser to return the vaporized alcohol to the still.

The reaction of amyl'alcohol and 3-methy1-A4- tetrahydrophthalic acid or anhydride results in the production of water and it is advisable to recarded,- or subsequently processed to reclaim the move the water from the reaction.

This may be done in a number of ways.

For example, the mixed reactants may be heated to boiling, the vapors condensed, and the condensate permitted to stratify. The alcohol layer may be retiirned to the still and the water layer discarded or further processed to reclaim the small quantities of alcohol and esters which itmay contain. 1

The continuous removal of the water formed during the reaction results in a considerable increase in the velocity of the esterification reaction and an increase in the yield of esters obtained from the process. I

The removal of water formed during the reaction may be facilitated by the addition of a third component. A procedure which has been found very satisfactory is the following: benzene is added to the mixture of the amyl alcohol and 3-methyl-A4-tetrahydrophthalic acid orits anhydride, and the ternary system so formed is heated to boiling. The vapors formed are condensed and permitted to stratify. The benzolalcohol layer,- namely the upper layer, is returned to the still and the water layer is dissmall quantities of alcohol and ester which it may contain. This procedure may be employed in batch or continuous operations, or otherwise.

Another way to prepare the amyl esters of 3-methyl-A4-tetrahydrophthalic acid involves the use of a catalyst which will facilitate the splitting off of water between the alcohol and the acid. Among the catalysts which may be employed, are sulfuric acid and anhydrous hydrogen chloride. When the latter is used, the mixture of alcohol and acid may be saturated with the dry hydrogen chloride, if desired.

The amyl esters of B-methyl-A-tetrahydrophthalic acid may also be prepared through the reaction of the acid chloride or other acid halide of 3-methyl-A 4-tetrahydrophthalic acid and the amyl alcohol.

- 'When this procedure is employed, it has been found that the use of a third component capable 'of reacting to remove the liberated hydrogen metallic derivative such as the'corresponding sodium, potassium, or lithium amylates.

Generally speaking, in, the process described herein, the reactants may be combined in any desired proportion, the excess of either component being separated from the reaction mass at the conclusion of the reaction by distillation or other suitable means.

The reactants may be mixed at the start of the reaction, or one of the components may be added to the other component during the course of the reaction. The reaction may be carried out batchwise, semi-continuously, continuously, or otherwise and the reactants may be combined in a concurrent or countercurrent manner, or otherwise.

The useof approximately two mols of alcohol to one mol of the acid or the anhydride will be amyl esters of 3-methyl-A4-tetrahydrophthalic acid, the mixture of esters so formed can beused as such, or they can be separated into their, individualcomponents by fractionation or by other suitable means. Among other meth6ds', vacuum distillation can esters. Illustrative of the preparation of amyl esters of 3-methyl-A4-tetrahydrophthalic acid by. the above methods is the following example:

Example 2 To a mixture of 83 parts by weight of smethyl-M-tetrahydrophthalic anhydride, and 220 parts by weight of normal amyl alcohol was added approximately 2parts by weight of 95% sulfuric acid. This mixture was refluxed at a temperature of between 135 and 145 C. for a period of approximately 46 hours. The water generated during the reaction was continuously removed by collecting the condensate in a trap, separating the layers, and returning the waterfree reaction products to the reaction flask. A quantity equivalent to.18 parts by weight of This ester .hadthe following physical properties:

Boiling point, I'm-183 C. at 3 mm. Density, D /4=0.9890 Refractive index, N 20/ D=l.4636

Any of the methods described herein may be employed in the preparation of the amyl" esters of 3-methyl-A4-tetrahydrophthalic acid. However, certain of the described procedures give better yields of .the amyl esters than others, depending upon the type of amyl alcohol employed in the reaction.

For example, the reaction of tertiaryamyl alcohol with 3-methyl-A4-tetrahydrophthalic acid can be effected by refluxing the reactants without the presence of any catalyst; the reaction,

found to be advantageous from the standpoint however, is somewhat slow and incomplete, and may be greatly accelerated by the addition of a catalyst. Sulfuric acid or hydrogen chloride may be added to assist in the removal of water formed by the reaction, and zinc dust may be added to catalyze the combination of the reaotants'. 1 I

A'preferred method is the reaction-of a metallic salt of 3-methyLA4-tetrahydrophthalic acid, such as the sodium salt, with a tertiary amyl halide or derivative, such as tertiary amyl chloride, suitably at elevated temperatures and pressures.

Similarly, the reaction of secondary amyl alcohol with. 3-methyl-A4-tetrahydrophthalic acid.

may be accelerated through the use of a suitable catalyst, such as gaseous hydrogen chloride.

The production of secondary amyl esters without the use of a catalyst is much slower than the production- 0f primary amyl esters employing either normal amyl alcohol or isoamyl alcohol and using no catalyst.

ment willbe observed in the reaction of certain of the secondary amyl'alcohols with 3-methyl- Ad-tetrahydrophthalic acid, or its anhydride, or

be used to isolate the pure amyl water was removed during the course of the rederivatives thereof. For example, when secondary butyl carbinol, or derivative thereof, is employed in the reaction, some tertiary and primary esters will be' obtained in the product.

Similarly, both pentanol-2 and pentanol-3 have a tendency togive a product containing derivatives in both the 2- and 3-positions respectively.

The amyl esters of 3-methyl-A4-tetrahydrophthalic acid are practically colorlessand odorless fluids.

They may be used as plasticizers for cellulose acetate, cellulose nitrate, natural gums, synthetic resins, and'resinous and plastic materials in general.

They may be applied in combination with other plasticizers in the formulation of plastics including lacquers, particularly those lacquers containing cellulose esters. They are particularly valuable as plasticizers for lacquer films. They may be used as plasticizers and softening agents for resins, plastics and gums which are to be molded,

extruded, cast or formed by any of the methods known tothe art. They also are valuable as intermediates in chemical synthesis.

Exemplary of their industrial utility is their use in theflpreparation of lacquer plasticizers. For this purpose, it is sometimes desirable. to employ substances possessing a fairly wide range in plasticizing characteristics. Mixed amylesters of 3-methyl-A4-tetrahydrophthalic acid such as are obtained by the reaction of mixtures con- In addition, a certain amount of rearrangetaining amyl alcohols with the acid or its anhydride, are particularly adapted to meet the requirements for such lacquer plasticizers. The use of these esters in combination with other esters, such as those derived from malelc acid or phthalic acid, also will be found to be desirable in certain cases.

On the other hand, it is often desirable to make use of substances having a fairly narrow boiling range. Amyl esters of 3-methyl-A4-tetrahydrophthalic acid or its anhydride, which have been prepared through the reaction of a single amyl alcohol with the requirements for such a substance.

In certain cases, the use of mixtures comprising certain or all of the amyl esters of 3-methyl- Al-tetrahydrcphthalic acid, or mixtures containing one or more of such esters incombination with one or more esters or derivatives of other acids, such as for example, maleic or phthalic acid, will be found to be desirable.

The use. of the amyl esters of 3-methyl-A4 tetrahydrophthalic anhydride as plasticizing agents is illustrated by the following examples:

. Example 3 A mixture of the following basic ingredients 1 Parts Ester gum -s 2.5 Nitrocellulose (/2 second) A 3-methyl-A4-tetrahydrophthalic acid n-amyl ester 2 5 was incorporated in 40 parts of a thinner of the following composition Parts Amyl alcohol Isopropyl acetate 13 Anhydrous ethyl alcohol 3 Toluol 34 Tro1uo1? 20 Pentacetate as 20 (Troluoi is a hydrocarbon solvent well known in the art. It isa mixture of hydrocarbons derived from the cracking of petroleum oil under conditions such as are employed in making motor fuel, and is predominantly non-aromatic in character with boiling range characteristics essentially similar to those of toluol.)

A clear, somewhat viscous solution was obthe acid'or anhydride, meet tained. This lacquer was applied to the surface of tinpanels and permitted to dry overnight. An adherent extensible, flexible film was found, which did not silk or crack when the tin panel was repeatedly bent through an angle of 180.

Example 4 A mixture 0': the following basic ingredients Parts Cellulose acetate 6.5

3-methyl-M-tetrahydrophthalic acid N-arnyl ester I. 0 5 was dissolved in 93 parts of a thinner of the fol-. lowing composition Parts Acetone Ethylene glycol monomethyl ether 20 Toluene s; 15* Isoprene acetate 15 v A clear, somewhat viscous solution wasv ob tained." This 'was used to coat several metal panels which were subsequently permitted to dry Example 5 Approximately 5 parts of ester gum, 10 parts of ethyl cellulose, and 5 parts of the N-amyl ester of S-methyl-A'i-tetrahydrophthalic acid was dissolved in 80 parts of a thinner having the following composition /8" mandrel Parts Pentasol 10 Pentacetate 20 Isopropyl ac a 13 Ethyl alcohol (anhydrous) 3 Toluol 34 Troluol 20 A clear, viscous solution was obtained, which was subsequently appliedto the surface of tin panels. A tough, adherent, extensible film was obtained. Plastics, resins, and resinous masses in general may be plasticized by the use of amyl esters of 3-methyl-A4-tetrahydrophthalic acid, either alone or in admixture with other plasticizing agents or solvents. Illustrative of such resins and plastics are the following: cellulose acetate, cellulose nitrate, ethyl cellulose, cellulose acetobutyrate, polyvinyl chloride, polyvinyl acetate, polyvinyl chloride-polyvinyl acetate co-polymers, polyvinyl acetal, polymerized acrylic acid, acrylic acid esters, or acrylic nitrile, polymerized methacrylic acid, methacrylic acid esters, or methacrylic nitrile, polyvinyl esters, hydrocarbon resins. polystyrene, p'olymethyl styrene, polyamide-polybasic acid plastic masses, and the like. Co-polymers obtained by the polymerization of two or more of the foregoing compounds also may be plasticized by the use of amyl esters of 3- methyl-A4-tetrahydrophthalic acid.

For certain uses, such as for lacquer plasticizing agents, it has been found advantageous in certain cases to use a mixture of the ester with a small quantity of the corresponding alcohol in order to neutralize any acidity which may be formed as the result of a slight hydrolysis of the ester.

My new amyl esters may be employed for many purposes.

For example, they may be employed (1) as solvents for synthetic and natural gums, plastics and resins; (2) as ingredients in the'preparation of lacquers,.spirit varnishes, oil varnishes, enamels, paints, and coating compositions generally; (3) as plasticizers for natural gums and resins such as shellac, kauri, sandarac, elemi,

, copal, dammar, casein, and rosin; (4) as plasresins; (5) as plasticizers for cellulosic plastics, such as cellulose nitrate and cellulose acetate;

and (6) as plasticizers for lacquer films.

The invention in its broadest aspects also includes the preparation of the monoamyl esters of 3-methyl-A4-tetrahydrophthalic anhydride. In

general, these compounds are of less importance industrially than the corresponding die-my esters. However, they have certain applications, as

for example, the preparation of mixed esters by 'eaction' with another alcohol, such as for example, N-butyl alcohol.

overnight. A colorless, clear, adherent, extensible film was formed. It did not silk or crack when tained as intermediates in the reactions in the As an' example, monoamyl esters may be obforegoing examples by stopping the reactions before completion and separating the monoamyi and diamyl esters by fractionation.

In the process claims, the term 3-methy1-A4- tetrahydrophthalic acid is intended to embrace the acid, or its anhydride, or mixtures of the same.

In the product claims, reference to the acid is merely by way of appellation of the final product regardless of how made and is therefore not intended to be limitative as many method for the production of the esters claimed herein.

While organic esters of particular types and procedures for the purpose of preparing such esters have been particularly described, it is to be understood that these are by way of illustration. Therefore, changes, omissions, additions, substitutions, and/or modifications may be made within the scope of the claims without departing from the spirit of the invention.

I claim: 1. An amyl ester of 3-methyl-A4-tetrahydrophthalic acid.

2. Di-primary-amyl ester of 3-methyl-A4- tetrahydrophthalic acid.

3. Di-secondary-amyl ester of 3-methyl-A4- tetrahydrophthalic acid.

4. Di-tertiary-amyl ester of 3-methyl-A4-tetrahydrophthalic acid.

5. A process for the preparation of an organic 7 ester comprising reacting 3-methyl-A4-tetrahydrophthalic acid with an amyl alcohol.

6. A process for the preparation of an organic ester comprising reacting 3-methyl-A4-tetrahydrophthalic acid with an amyl alcohol in the presence of sulfuric acid.

7. A process for the preparation of an organic ester comprising reacting 3-methyl-A4-tetrahy drophthalic acid with an amyl alcohol in the presence of anhydroushydrogen chloride.

8. A process for the preparation of an organic .ester comprising reacting 3-methyl-A4-tetr'ahydrophthalic acid with'an amyl alcohol in the presence of benzene; the presence of said benzene facilitating separation from the reaction zone of water formed during the reaction.-

9. An amyl ester of 3-methyl-A4-tetrahydrophthalic acid having the formula:

FRANK J. SODAY. 

